Field
The present invention relates to a rechargeable battery that discharges internal pressure that reaches a predetermined value.
Description of the Related Art
A rechargeable battery can be repeatedly charged and discharged, unlike a primary battery. A rechargeable battery of a small capacity is used for a small portable electronic device like a mobile phone or a laptop computer or a camcorder, and a rechargeable battery of a large capacity is used as a power source for driving a motor of a hybrid vehicle and an electric vehicle.
For example, a rechargeable battery includes an electrode assembly that performs a charge and discharge operation, a case that houses the electrode assembly and an electrolyte solution, a cap plate that is coupled to an opening of the case, and an electrode terminal that is connected to the electrode assembly to be installed in the cap plate.
In order to discharge an internal pressure in the case, the cap plate includes a vent hole, has a vent plate in the vent hole, and has an external short circuit unit, which is an overcharge safety device. The external short circuit unit has a connection plate of a mutual insulation state and a membrane, and thus when an internal pressure increases due to overcharge, the external short circuit unit short-circuits an inverted membrane from the connection plate.
The connection plate is connected to a negative terminal, and the membrane is connected to a cap plate that is electrically connected to a positive terminal. Therefore, the membrane is inverted to contact the connection plate and thus safely discharges a current that is charged in an electrode assembly. Because such a rechargeable battery has a vent hole, a vent plate, and an external short circuit unit, the rechargeable battery has a complex structure and an increased production cost.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.